Sensitive High-performance Liquid Chromatographic Method Research Articles

A novel liquid chromatography-fluorescence method for the determination of delafloxacin in human plasma.

Delafloxacin is a novel fluoroquinolone antibiotic that was approved by the European Medicine Agency to treat bacterial infections of the skin and underlying tissues, and community-acquired pneumonia. Despite being in the market since 2019 in the European Union, there is no published liquid chromatography-fluorescence method for delafloxacin quantification in biological samples. A novel, rapid, and sensitive high-performance liquid chromatographic method was developed to determine delafloxacin in human plasma using its native fluorescence. Plasma delafloxacin concentrations were determined by reverse-phase chromatography with fluorescence detection at 405/450nm of excitation/emission wavelengths. Delafloxacin was separated on a Kromasil C18 column 250 × 4.6mm id, 5 µm using isocratic elution. The mobile phase was a mixture of 0.05% trifluoroacetic acid/acetonitrile (52/48). Retention times were 5.4 and 11.6 min for delafloxacin and valsartan (internal standard), respectively. Regression calibration curves were linear over the range of 0.1-2.5 µg/mL. The lower limit of detection was 0.05 µg/mL, and the lower limit of quantification was 0.1 µg/mL. Accuracy and precision were always<11%, and the limit of quantification was<16%. Mean recovery was 98.3%. This method can be applied to determine delafloxacin in human plasma and could be useful to perform pharmacokinetic studies.

Effect of Sijunzi Pills on Pharmacokinetics of Omeprazole in Beagle Dogs by HPLC-UV: A Herb-Drug Interaction Study.

A sensitive high-performance liquid chromatography (HPLC-UV) method for determination of omeprazole in beagle dog plasma was developed and to investigate the effect of Sijunzi pills (SJZPs) on the pharmacokinetics of omeprazole in beagle dogs. The beagle dog plasma was extracted with ethyl acetate and n-hexane under alkaline conditions. Omeprazole and internal standard (IS, fluconazole) were separated on an XDB-C18 column, and acetonitrile and 0.1% trifluoroacetic acid were used as the mobile phase. Omeprazole and IS were detected by using a diode array detector. This experiment adopts the experimental design of double-cycle self-control. In the first cycle (group A), six beagle dogs were given omeprazole 0.67 mg/kg orally in a single dose. In the second period (group B), the same six beagle dogs were orally given SJZPs 0.2 g/kg twice a day for 7 consecutive days, and then, omeprazole was orally given. At the different time points after omeprazole was given in the two periods, the blood samples were collected. The concentration of omeprazole was detected by the developed HPLC method. DAS 2.0 was used to calculate the pharmacokinetic parameters of omeprazole. Under the current experimental conditions, this UPLC method showed good linearity in the detection of omeprazole. Interday and intraday precision did not exceed 10%, and the range of accuracy values were from −1.43% to 2.76%. The results of extraction recovery and stability met the requirements of FDA approval guidelines of bioanalytical method validation. The Cmax of omeprazole in group B was 61.55% higher than that in group A, and the AUC(0−t) and AUC(0−∞) of omeprazole in group B were 63.96% and 63.65% higher those that in group A, respectively. At the same time, the clearance (CL) and apparent volume of distribution (Vd) decreased in group B. In this study, an HPLC method for the determination of plasma omeprazole concentration was established. SJZPs could inhibit the metabolism of omeprazole and increase the concentration of omeprazole in beagle dogs. It is suggested that when SJZPs are combined with omeprazole, attention should be paid to the herb-drug interactions and possible adverse reactions.

Application of Solid Phase Extraction and High-Performance Liquid Chromatography with Fluorescence Detection to Analyze Bisphenol A Bis (2,3-Dihydroxypropyl) Ether (BADGE 2H2O), Bisphenol F (BPF), and Bisphenol E (BPE) in Human Urine Samples.

In this study, we propose a simple, cost-effective, and sensitive high-performance liquid chromatography method with fluorescence detection (HPLC-FLD) for the simultaneous determination of the three bisphenols (BPs): bisphenol A bis (2,3-dihydroxypropyl) ether (BADGE 2H2O), bisphenol F (BPF), and bisphenol E (BPE) in human urine samples. The dispersive solid phase extraction (d-SPE) coupled with solid phase extraction (SPE) procedure performed well for the analytes with recoveries in the range of 74.3–86.5% and relative standard deviations (RSD%) less than 10%. The limits of quantification (LOQs) for all investigated analytes were in the range of 11.42–22.35 ng mL−1. The method was validated at three concentration levels (1 × LOQ, 1.5 × LOQ, and 3 LOQ). During the bisphenols HPLC-FLD analysis, from 6 min a reinforcement (10 or 12) was used, therefore analytes might be identified in the small volume human urine samples. The results demonstrated clearly that the approach developed provides reliable, simple, and rapid quantification and identification of three bisphenols in a urine matrix and could be used for monitoring these analytes.

Evaluation of intraocular penetration of levofloxacin by high performance liquid chromatography

AIM: To evaluate the levofloxacin eye drop into human eye penetration, levofloxacin eye drop concentrations in human ocular aqueous of 33 patients undergoing cataract surgery were measured by high performance liquid chromatography (HPLC). METHODS: Totally 33 volunteer patients who scheduled for phacoemulsification surgery received one drop of levofloxacin every 6h for 3d before and on the day of surgery, administration of drug was stopped 1h before surgery. Levofloxacin concentration in aqueous humor was measured by HPLC method with fluorescence detector. RESULTS: A simple, effective and sensitive HPLC method for determination of levofloxacin in human ocular aqueous was validated. Linearity was shown for levofloxacin concentration over a wide range of 1.95×10-3-1.50 µg/mL. The mean aqueous level of levofloxacin was 0.3399±0.03405 µg/mL. CONCLUSION: Results from the present study demonstrate that topical administration of levofloxacin 0.5% before cataract surgery with routine dose (one drop every 6h) unable to reach MIC90 for most common microorganism causing acute bacterial endophthalmitis.

Fruits of Vitex doniana sweet: toxicity profile, anti-inflammatory and antioxidant activities, and quantification of one of its bioactive constituents oleanolic acid

BackgroundVitex doniana Sweet fruit, an under-utilised crop specie of Ghana, has not been validated for its ethnomedical use in managing inflammatory conditions. Therefore, the study sought to investigate its anti-inflammatory and antioxidant activities as well as isolate and quantify one of its active constituents. Materials and methodsIn-vivo anti-inflammatory activity of the methanol fruit extract was evaluated using the carrageenan-induced oedema model in chicks. The in-vitro antioxidant property was also investigated using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The acute and subacute toxicity studies of the fruit extract were evaluated in rodent models. ResultsNo signs of autonomic and central nervous system stimulation/depression were recorded. The LD50 by oral route, was estimated to be beyond 3000 mg/kg. Subacute studies revealed an increase in red blood cell and lymphocyte counts. Liver enzymes, serum proteins and bilirubin levels did not significantly increase. The crude extracts at doses of 10, 30 and 100 mg/kg inhibited paw oedema considerably. The ethyl acetate fraction showed the highest antioxidant activity (IC50 = 99.35 ± 0.77 μg/mL). Oleanolic acid, isolated from the ethyl acetate extract, showed significant anti-inflammatory and antioxidant activities. A sensitive high-performance liquid chromatography method for the detection and estimation of oleanolic acid, as a biomarker compound for V. doniana fruit, was developed and validated for quality assurance purposes. ConclusionThe extract of V. doniana fruits possesses considerable anti-inflammatory and antioxidant properties and was non-toxic under laboratory conditions.

Development and validation of RP-HPLC method for estimation of brexpiprazole in its bulk and tablet dosage form using Quality by Design approach

BackgroundA new, sensitive, suitable, clear, accurate, and robust reversed-phase high-performance liquid chromatography (RP-HPLC) method for the determination of brexpiprazole in bulk drug and tablet formulation was developed and validated in this research. Surface methodology was used to optimize the data, with a three-level Box-Behnken design. Methanol concentration in the mobile phase, flow rate, and pH were chosen as the three variables. The separation was performed using an HPLC method with a UV detector and Openlab EZchrom program, as well as a Water spherisorb C18 column (100 mm × 4.6; 5m). Acetonitrile was pumped at a flow rate of 1.0 mL/min with a 10 mM phosphate buffer balanced to a pH of 2.50.05 by diluted OPA (65:35% v/v) and detected at 216 nm.ResultThe developed RP-HPLC method yielded a suitable retention time for brexpiprazole of 4.22 min, which was optimized using the Design Expert-12 software. The linearity of the established method was verified with a correlation coefficient (r2) of 0.999 over the concentration range of 5.05–75.75 g/mL. For API and formulation, the percent assay was 99.46% and 100.91%, respectively. The percentage RSD for the method’s precision was found to be less than 2.0%. The percentage recoveries were discovered to be between 99.38 and 101.07%. 0.64 μg/mL and 1.95 μg/mL were found to be the LOD and LOQ, respectively.ConclusionThe developed and validated RP-HPLC system takes less time and can be used in the industry for routine quality control/analysis of bulk drug and marketed brexpiprazole products.Graphical abstract

Development of a highly sensitive HPLC method for the simultaneous determination of eight biogenic amines in aquatic products

AbstractA highly sensitive high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of eight biogenic amines in aquatic products. The biogenic amines in the sample were extracted with 5% trichloroacetic acid, derived with dansyl chloride (Dns-Cl) and quantified by a UV detector. The results showed that tryptamine (TRY), 2-phenethylamine (PHE), putrescine (PUT), cadaverine (CAD), histamine (HIS), tyramine (TPY), spermidine (SPD), and spermine (SPM) were effectively separated in 18 min in the range of 0.1–50 mg/kg with a good linear coefficient (r2 &gt; 0.999). The detection limits (LODs) of the eight biogenic amines were 0.007–0.021 mg/kg while the limits of quantification (LOQs) were 0.024–0.069 mg/kg with the recoveries basically between 68 and 123%. The determination of eight biogenic amines in five commercial fermented aquatic products indicating that the developed method could be applied for the simultaneous detection of biogenic amines in multiple aquatic products.

SIMULTANEOUS METHOD FOR THE ESTIMATION OF BEDAQUILINE AND DELAMANID IN HUMAN PLASMA USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Objective: A specific, simple and sensitive high-performance liquid chromatographic method for the estimation of Bedaquiline (BDQ) and Delamanid (DLM) in human plasma was developed.&#x0D; Methods: The method involved deproteinization and further extracted the analyte using Solid Phase Extraction (SPE) cartridge and analysed using C18 column with the wavelength set at 231 nm. The isocratic mobile phase consisted of 10 mmol ammonium acetate buffer containing 0.25% acetic acid and 0.02% trifluoroacetic acid and acetonitrile in the ratio of 20:80(v/v). The validation parameters were evaluated. The method was applied to estimate plasma BDQ and DLM collected from five MDR-TB patients.&#x0D; Results: Well resolved peaks of BDQ and DLM at retention times of 5.4 and 2.6 min were obtained respectively. The calibration curve was linear over a range of 0.01–10.0 µg/ml for both BDQ and DLM. The intra-and inter-day relative standard deviations for standards were below 10%. The recoveries for BDQ ranged from 101% to 107% and 98% to 107 % for DLM respectively.&#x0D; Conclusion: A specific and sensitive method for simultaneous determination of BDQ and DLM in plasma using high-performance liquid chromatography was developed. This method can be used in clinical studies to evaluate drug exposure.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC ESTIMATION METHOD FOR TRANSDERMAL DIFFUSION STUDY OF GRANISETRON

Objective: The study is aimed to develop a simple, isocratic and sensitive reversed-phase high-performance liquid chromatography method for the analysis of granisetron during transdermal permeation studies through porcine ear epithelium.&#x0D; Methods: A reversed-phase (C18) column was used with ultraviolet detection at 210 nm. Selected mobile phase contained 25% (v/v) of acetonitrile and 75% (v/v) of 0.25 mM potassium dihydrogen orthophosphate solution pH adjusted to 3.0 using 1% orthophosphoric acid solution.&#x0D; Results: Calibration curve showed good linearity over 0.1–30 μg/mL concentration range of porcine ear permeates in 80% ethanol and 20% water (blank permeates). The applicability of the method was demonstrated by the analysis of diffusion study samples of granisetron through porcine ear epithelium and the steady-state permeability flux (J) from ethanolic solution was found to be 4.707 µg/square cm/h.&#x0D; Conclusion: The developed method can be used in the analysis of diffusion study samples of granisetron transdermal formulations through the porcine ear epithelium.

HPLC Determination of Formaldehyde in Flour Samples using 2,4,6-Trichlorophenyl Hydrazine as Derivatization Reagent

A new simple and sensitive high-performance liquid chromatography (HPLC) method for the determination of formaldehyde in flour samples has been developed. Formaldehyde was quantified after derivatization with a readily available reagent, 2,4,6-trichlorophenyl hydrazine (TCPH) under basic conditions. The formaldehyde-TCPH derivative was eluted with chromatographic mobile phase of 70:30 (v/v) acetonitrile:water at a flow rate of 1.0 mL min–1; wavelength, 222 nm; injection volume, 50 μL, using a C18 ODS Hypersil column (250 mm × 4.5 mm, 5 μm). The calibration curve was linear over the range of 0.001-10 μg mL-1 with R2 = 0.999. Recoveries at three different concentration levels (0.1, 1.0 and 5 μg mL-1) ranged from 92.0-101.7% with RSD less than of 2.2%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 1.0 ng mL-1, respectively. The developed method was used for the determination of formaldehyde in various flour-based samples.

Fruits of &lt;i&gt;Vitex Doniana&lt;/i&gt; Sweet: Toxicity Profile, Anti-Inflammatory and Antioxidant Activities, and Quantification of One of its Bioactive Constituents Oleanolic Acid

Background: Vitex doniana Sweet fruit, an under-utilised crop specie of Ghana, has not been validated for its ethnomedical use in managing inflammatory conditions. Therefore, the study sought to investigate its anti-inflammatory and antioxidant activities as well as isolate and quantify one of its active constituents. Methods: In-vivo anti-inflammatory assay was done using the carrageenan- induced oedema model in chicks. The in-vitro antioxidant property was also investigated using the 2, 2-diphenyl-1-picrylhydrayl radical scavenging assay. The acute and subacute toxicity studies of the fruit extract were evaluated in rodent models. Results: No signs of autonomic and central nervous system stimulation/depression were recorded. The median lethal dose (LD50 ), by oral route, was estimated to be beyond 3000 mg/kg body weight. Subacute studies revealed an increase in red blood cell and lymphocyte counts. Liver enzymes, serum proteins and bilirubin levels did not significantly increase. The crude extracts at doses of 10, 30 and 100 mg/kg inhibited paw oedema considerably. The ethyl acetate fraction showed the highest antioxidant activity (half-maximal inhibitory concentration, IC50 = 99.35 ± 0.77 µg/mL). 3β-hydroxyolean-12-en-28-oic acid (oleanolic acid), isolated from the ethyl acetate extract, showed significant anti-inflammatory and antioxidant activities. A sensitive high-performance liquid chromatography method for the detection and estimation of oleanolic acid, as a biomarker compound for V. doniana fruit, was developed and validated for quality assurance purposes. Conclusion: The extract of V. doniana possesses considerable anti-inflammatory and antioxidant properties and was non-toxic under laboratory conditions.

Extraction and analysis of oleanolic acid and ursolic acid from apple processing waste materials using ultrasound-assisted extraction technique combined with high performance liquid chromatography

The aim of the present study was to develop a is simple, effective, eco-friendly, reproducible and high-yield two-stage ultrasound-assisted extraction (UAE) procedure combined with quantitative determination high performance liquid chromatographic (HPLC) method for obtaining isomeric triterpene acids - oleanolic acid (OA) and ursolic acid (UA) in the crystalline dried powdered form from apple processing agro-industrial waste material. A rapid, sensitive and specific HPLC method was developed and validated with respect to robustness, specificity, linearity-range, accuracy, precision and sensitivity. The effect of the nature and the volume of the extraction solvent, the extraction time and the sample size on the extraction efficiency were investigated. The optimal conditions for high-yield extraction were found.

Method Development and Validation of Metoprolol and Felodipine by using RP-HPLC in Bulk and Pharmaceutical Dosage Form

The main objective of this research is to develop and validate a simple, specific, precise, sensitive, cost effective and rapid Reversed-Phase High-Performance Liquid Chromatographic (RP-HPLC) method for simultaneous quantification of Felodipine and Metoprolol in bulk and pharmaceutical dosage forms. The separation of the analytes were carried out on a X-bridge phenyl column with a moving phase composed of 0.1 % Tri ethyl amine: acetonitrile (30:70 v/v) delivered at a stream of 1.0 ml/min, and separation has been observed by UV detector, at a detection wavelength of 235 nm. This method was proven to be linear over a concentration limit of 10-150 µg/ml for Metoprolol, 2-30 µg/ml for Felodipine with correlation coefficient of 0.999. The retention time of Metoprolol and Felodipine were 2.936, 4.535 minutes respectively. To separate Metoprolol and Felodipine peaks a run time of 8 min. was used. The validation results were in good agreement with acceptable limits. RSD values which are less than 2.0 % indicating the accuracy and precision of this method. Hence it was evident that the proposed method was said to be a suitable one for the regular analysis and quality control of pharmaceutical preparations which contain these active drugs either individually or in combination.

Quantification of letermovir in human serum using high-performance liquid chromatography with diode array detection

A simple, rapid, cost-effective and sensitive high-performance liquid chromatography method with diode array detection was developed and validated for the quantification of letermovir, a compound approved for prophylaxis of cytomegalovirus infection and disease in adult recipients of an allogeneic hematopoietic stem cell transplant. Sorafenib was used as internal standard. Samples were pre-treated by liquid–liquid extraction with tert-butyl methylether. Separation was achieved on a XTerra® RP18 column (150 × 2.1 mm, 5 µm) at 30 °C using gradient elution with a mobile phase of 20 mM ammonium bicarbonate pH 7.9 (mobile phase A) and acetonitrile:20 mM ammonium bicarbonate (9:1 v/v) (mobile phase B). Samples were eluted at a flow rate of 0.3 mL/min throughout the 20-min run. UV wavelength mode was used, letermovir and sorafenib were monitored at 260 nm. The calibration curve was linear in a concentration range of 25–5000 ng/mL with correlation coefficients ≥ 0.99. Intra-day and inter-day accuracy expressed as relative error were −11.4–20% and −7.96–10.62%, respectively. Precision expressed as coefficient of variation was 1.44–3.15% (intra-day) and 1.17–1.93% (inter-day). The method was successfully applied for analysis of 128 letermovir levels demonstrating its usefulness for letermovir monitoring in routine clinical practice.

A Liquid Chromatographic Analysis of Deferasirox in Human Breast Milk with Fluorimetric Detection

To determine deferasirox in human breast milk a novel, sensitive high-performance liquid chromatographic method with fluorescence detection has been developed. Precolumn derivatization process is applied to achieve fluorescent analyte using 4-bromomethyl-7-methoxy coumarin (BrMmC) as a reagent and dibenzo-18-crown-6-ether as catalyst. The method depends on reverse phase chromatography. C18 column has been used with 150 × 4.6 mm, 5 μm particle size and the mobile phase consisting of acetonitrile:phosphate buffer (20 mM, pH 3) (70:30, v/v) with a flow rate of 1.0 mL/min. Fluorescence detection at 390 nm is provided with an excitation at 320 nm The linear range is 0.01–1.0 μg/mL. The mean recovery has been calculated as 100.7% with a relative standard deviation (RSD) value less than 2%. The developed method was successfully applied for the determination of deferasirox in human breast milk samples.

HPLC determination of 9,10-anthraquinone-2-carboxylic acid in serum and its application to pharmacokinetic study

A simple and sensitive high-performance liquid chromatographic (HPLC) method involving UV detection was developed for the determination of 9,10- anthraquinone-2-carboxylic acid (AQCA) in rabbit serum. A reverse-phase column (Lichrosher ®100RP-18) was eluted with a mobile phase of 0.4% phosphoric acid: acetonitrile (7:3) / methanol = 45 : 55 at a flow rate of 1.2 mL/min. The UV absorbance was monitored at 256 nm. After a simple clean- up procedure, the limit of quantitation achieved was 0.6 μg/mL and the standard curve was found to be linear over the serum concentration of 0.6 - 18μg/mL. The intra-assay and inter-assay coefficient of variance in serum was less than 2%, and the recovery was 96.98%. The established HPLC method was applied to the study of pharmacokinetics and bioavailability of 9,10- anthraquinone-2-carboxylic acid (AQCA). Eighteen healthy rabbits were divided into three groups and given intravenous (i.v.), oral and rectal administrations of different AQCA preparations with a single dose of 10 mg/kg. Blood samples were collected and AQCA concentrations in serum were analyzed. The results were performed with Winnolin programs and the ANOVA test (α = 0.05) was used to compare the pharmacokinetic parameters of AQCA in the three regimens. For the i.v. route, the t( 1/2 ) and AUC were 4.43 ± 0.13 hrs and 141.79 ± 7.84 μg*hr/mL, respectively. Parameters for the oral route were: T(max) = 7.17 ± 0.41 hrs; t( 1/2 ) = 15.32 ± 1.86 hrs; MRT = 20.02 ± 2.07 hrs and AUC = 107.53 ± 4.50 μg*hr/mL. The oral route indicated a slower absorption rate, a longer residence time and a lower extent of the AQCA absorption. For the rectal route, T(max) occurred at 1.58 ± 0.20 hrs, the t( 1/2 ) was 5.67 ± 0.82 hrs and the AUC was 121.18 ± 6.19 μg*hr/mL. The results indicated that the rate and extent of AQCA rectal absorption were better compared to those of the oral route. At this dose, the absolute bioavailabilities of AQCA were 0.876 and 0.872 for oral and rectal administrations, respectively. The differences of these pharmacokinetic parameters might be due to the physicochemical properties of AQCA in different conditions.

A dose-dependent pharmacokinetic study of levodopa by intramuscular administration in rabbits

The dose-dependent pharmacokinetics of levodopa (L-dopa) was studied in rabbits by intramuscular administration. Three different doses of L-dopa/carbidopa (2/0.5, 5/1.25, and 10/2.5 mg/kg) were administered to six male rabbits via an intramuscular (IM) route, and one dose of L-dopa/carbidopa (2/0.5 mg/kg) was administered via an intravenous (IV) route with a washout period of 1-week between different doses. Plasma samples were collected after each treatment and the concentrations of L-dopa and 3-O-methyldopa (an L-dopa metabolite, 3-OMD) were measured by a sensitive high-performance liquid chromatographic (HPLC) method. Subsequently, these measurements were used to determine the pharmacokinetic behavior of L-dopa and 3-OMD. The results indicated that the absorption of L-dopa was fast with the time to the peak within 30 min, but the formation of 3-OMD was slow with the time to the peak of 120-180 min after IM administration. The IM bioavailability of L-dopa was in the range of 0.70-1.21, and the relative ratios of the formation of 3-OMD at different doses of L-dopa were in the range of 0.79-1.24. No statistically significant difference could be observed for IM bioavailability of L-dopa or for the relative ratios of the formation of 3-OMD in this dose range. The elimination half-lives of L-dopa and 3-OMD also exhibited no significant differences for each dose after IM administration. In addition, both the area under the curve (AUC) and maximum plasma concentration (Cmax) values of L-dopa and 3-OMD increased proportionally over the dose range of 2/0.5-10/2.5 mg/kg for L-dopa/carbidopa, suggesting that L-dopa and 3-OMD obeyed dose-independent pharmacokinetics.

A sensitive RP-HPLC method for estimation of artemether from polymeric nanoparticles after pre-column acid treatment using UV-visible detector

Artemether; a sesquiterpene lactone is widely used for the treatment of malaria as artemisinin-based combination therapy (ACT). The present work involves the development and validation of sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) method for quantification of artemether (ART) in polymeric nanoparticles. ART was transformed to α, β-unsaturated decalones by pre-column acid treatment to enhance the sensitivity of chromophoric group lacking ART for quantification by HPLC-UV. Waters Spherisorb® 5 µm ODS(C18) column (4.6*250 mm) with gradient elution by mobile phase comprising of ACN and PBS (10 mM; pH 6.0) was used to separate acid-treated ART. The analysis was carried at λmax of 253 nm with 20 min and 20 µL run time and injection volume, respectively. The method was found to be linear in the concentration range of 0.5–10 µg mL−1 with 0.09 µg mL−1 and 0.27 µg mL−1 as LOD and LOQ respectively. Further, the method was also found to be specific for ART in presence of blank polymeric nanoparticles, accurate (% average recovery rate 101.7 ± 1.68%), precise (RSD <2%), and robust. The method was successfully used to determine % entrapment efficiency and in vitro release of ART-loaded polymeric nanoparticles with HPLC using a UV-visible detector.

A sensitive HPLC-UV method for quantifying vancomycin in biological matrices: Application to pharmacokinetic and biodistribution studies in rat plasma, skin and lymph nodes

Vancomycin (VCN) is an antibiotic used in the treatment of methicillin-resistant Staphylococcus aureus (MRSA)-derived infections. As it has a relatively narrow therapeutic window, it is imperative to develop a sensitive and reliable analytical method for drug monitoring and pharmacokinetic purposes. In the present study, quick sample preparations and a sensitive high-performance liquid chromatography method using UV detection (HPLC-UV) have been developed and validated. The analytical method for detection and quantification of VCN in rat plasma, skin and lymph node samples was validated based on the Food and Drug Administration (FDA) and European Medicine Agency (EMEA) bioanalytical method validation guidelines. The optimised plasma sample preparation involved a simple protein precipitation step, with extraction recovery of 100.3 ± 0.92 %. VCN in all biological matrices was analysed in a HPLC-UV system (215 nm) using a Cortecs® C18 column (4.6 × 150 mm, 2.7 μm particle size) fitted with a guard cartridge set at 20 °C. Reverse phase HPLC under gradient conditions, with mobile phase consisting of 20 mM phosphate buffer containing 0.5 % v/v of triethylamine and a mixture of methanol – acetonitrile (70:30, v/v), and runtime of 12 min/sample was employed. The calibration standards used for plasma ranged between 0.1−50 μg/ml, while in the skin and lymph node matrices, standards ranged between 0.05−50 μg/ml with correlation coefficients (R2) of ≥ 0.9995 for all matrices. The method was selective, sensitive, accurate and precise for detecting and quantifying VCN in the biological matrices used. The validated method was successfully utilised in the detection of VCN in a pharmacokinetic and organ biodistribution study carried out in rats following oral and IV bolus administration of the drug. This validated bioanalytical method offers a wide range of potential applications in clinical therapeutic drug monitoring, pharmacokinetics and toxicology.

High-Performance Liquid Chromatography for Therapeutic Drug Monitoring of Serum Lenvatinib.

Therapeutic drug monitoring (TDM) and dose adjustment of lenvatinib may be beneficial in the treatment of radioiodine-refractory thyroid cancer, by maximizing antitumor effects and minimizing adverse drug reactions. The aim of this study was, therefore, to develop and validate a high-performance liquid chromatography method using an ultraviolet detection system for routine serum lenvatinib detection in patients with thyroid cancer. Serum specimens, spiked with an internal standard, were treated by a solid-phase extraction through an octadecylsilyl silica cartridge. Lenvatinib and internal standard were concomitantly separated from serum using a conventional octadecylsilyl silica column through isocratic elution, using a mobile phase consisting of 0.02 mol/L sodium phosphate (pH 6.7) and acetonitrile (50/50, vol/vol) at a flow rate of 1.0 mL/min. The detection wavelength was set at 244 nm. Serum samples from 5 patients were used for clinical validation of the method. The calibration curve for lenvatinib was linear (Pearson correlation coefficient, r = 0.9998) over the concentration range of 6.25-400 ng/mL, with a lower limit of quantification of 6.25 ng/mL. Extraction recoveries for lenvatinib were 97% or more, with coefficients of variation less than 2.2%. The coefficients of variation for intraday and interday assays were less than 4.7% and 6.0%, respectively. This sensitive high-performance liquid chromatography method can be used for lenvatinib therapeutic drug monitoring when liquid chromatography-tandem mass spectrometry facilities are unavailable.